1. Field of the Invention
The present invention relates a navigation system and a bypass route setting method to set a bypass route relative to a travel route ahead of a vehicle while the vehicle is traveling along a travel route set by route search processing.
2. Description of the Related Art
In the related art, there is a known communication navigation system in which a route search request is transmitted to a map information providing communication center device from a communication navigation terminal, and the map information providing communication center device conducts a search for an optimal route and returns a result thereof to the communication navigation terminal (refer to JP 2003-75178 A, for example).
Further, in the related art, there is a known configuration in which a route to bypass a congested road is returned to a vehicle which has transmitted a current position and a destination to a road information center (refer to JP 2004-61429 A, for example).
According to the configuration disclosed in JP 2003-75178 A, route search processing is performed on a center side (external device) in response to a route search request transmitted from a vehicle side, and an optimal travel route obtained as a result thereof is returned to the vehicle side. This point is the same as the configuration disclosed in JP 2004-61429 A. According to the configurations disclosed in JP 2003-75178 A and JP 2004-61429 A, the optimal travel route obtained as the result of the route search processing performed on the center side can be acquired. However, in the case where traffic congestion, various kinds of traveling regulations, and the like take place in a travel route ahead while the vehicle travels along the mentioned optimal travel route, there is a problem in which the travel route cannot be reset by specifying a road to be avoided. For example, it may be possible to designate a link number and a node number of the road to be avoided on the vehicle side, but map data used in the vehicle is not always the same as map data used on the center side. Therefore, the same road may not be specified even though the link number and the node number are designated, and a place of the road to be avoided may not be found by the center side.